/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
using System;
using java = biz.ritter.javapi;

using org.apache.commons.codec;

namespace org.apache.commons.codec.language
{

    /**
     * Encodes a string into a Soundex value. Soundex is an encoding used to relate similar names, but can also be used as a
     * general purpose scheme to find word with similar phonemes.
     * 
     * @author Apache Software Foundation
     * @version $Id: Soundex.java 794026 2009-07-14 19:21:23Z ggregory $
     */
    public class Soundex : StringEncoder
    {

        /**
         * This is a default mapping of the 26 letters used in US English. A value of <code>0</code> for a letter position
         * means do not encode.
         * <p>
         * (This constant is provided as both an implementation convenience and to allow Javadoc to pick
         * up the value for the constant values page.)
         * </p>
         * 
         * @see #US_ENGLISH_MAPPING
         */
        public static readonly String US_ENGLISH_MAPPING_STRING = "01230120022455012623010202";

        /**
         * This is a default mapping of the 26 letters used in US English. A value of <code>0</code> for a letter position
         * means do not encode.
         * 
         * @see Soundex#Soundex(char[])
         */
        public static readonly char[] US_ENGLISH_MAPPING = US_ENGLISH_MAPPING_STRING.toCharArray();

        /**
         * An instance of Soundex using the US_ENGLISH_MAPPING mapping.
         * 
         * @see #US_ENGLISH_MAPPING
         */
        public static readonly Soundex US_ENGLISH = new Soundex();


        /**
         * Encodes the Strings and returns the number of characters in the two encoded Strings that are the same. This
         * return value ranges from 0 through 4: 0 indicates little or no similarity, and 4 indicates strong similarity or
         * identical values.
         * 
         * @param s1
         *                  A String that will be encoded and compared.
         * @param s2
         *                  A String that will be encoded and compared.
         * @return The number of characters in the two encoded Strings that are the same from 0 to 4.
         * 
         * @see SoundexUtils#difference(StringEncoder,String,String)
         * @see <a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_de-dz_8co5.asp"> MS
         *          T-SQL DIFFERENCE </a>
         * 
         * @throws EncoderException
         *                  if an error occurs encoding one of the strings
         * @since 1.3
         */
        public int difference(String s1, String s2)
        {// throws EncoderException {
            return SoundexUtils.difference(this, s1, s2);
        }

        /**
         * The maximum length of a Soundex code - Soundex codes are only four characters by definition.
         * 
         * @deprecated This feature is not needed since the encoding size must be constant. Will be removed in 2.0.
         */
        private int maxLength = 4;

        /**
         * Every letter of the alphabet is "mapped" to a numerical value. This char array holds the values to which each
         * letter is mapped. This implementation contains a default map for US_ENGLISH
         */
        private readonly char[] soundexMapping;

        /**
         * Creates an instance using US_ENGLISH_MAPPING
         * 
         * @see Soundex#Soundex(char[])
         * @see Soundex#US_ENGLISH_MAPPING
         */
        public Soundex()
        {
            this.soundexMapping = US_ENGLISH_MAPPING;
        }

        /**
         * Creates a soundex instance using the given mapping. This constructor can be used to provide an internationalized
         * mapping for a non-Western character set.
         * 
         * Every letter of the alphabet is "mapped" to a numerical value. This char array holds the values to which each
         * letter is mapped. This implementation contains a default map for US_ENGLISH
         * 
         * @param mapping
         *                  Mapping array to use when finding the corresponding code for a given character
         */
        public Soundex(char[] mapping)
        {
            this.soundexMapping = new char[mapping.Length];
            java.lang.SystemJ.arraycopy(mapping, 0, this.soundexMapping, 0, mapping.Length);
        }

        /**
         * Creates a refined soundex instance using a custom mapping. This constructor can be used to customize the mapping,
         * and/or possibly provide an internationalized mapping for a non-Western character set.
         * 
         * @param mapping
         *            Mapping string to use when finding the corresponding code for a given character
         * @since 1.4
         */
        public Soundex(String mapping)
        {
            this.soundexMapping = mapping.toCharArray();
        }

        /**
         * Encodes an Object using the soundex algorithm. This method is provided in order to satisfy the requirements of
         * the Encoder interface, and will throw an EncoderException if the supplied object is not of type java.lang.String.
         * 
         * @param pObject
         *                  Object to encode
         * @return An object (or type java.lang.String) containing the soundex code which corresponds to the String
         *             supplied.
         * @throws EncoderException
         *                  if the parameter supplied is not of type java.lang.String
         * @throws IllegalArgumentException
         *                  if a character is not mapped
         */
        public Object encode(Object pObject)
        { //throws EncoderException {
            if (pObject is java.lang.StringJ) pObject = ((java.lang.StringJ)pObject).ToString();
            if (!(pObject is String))
            {
                throw new EncoderException("Parameter supplied to Soundex encode is not of type java.lang.String");
            }
            return soundex((String)pObject);
        }

        /**
         * Encodes a String using the soundex algorithm.
         * 
         * @param pString
         *                  A String object to encode
         * @return A Soundex code corresponding to the String supplied
         * @throws IllegalArgumentException
         *                  if a character is not mapped
         */
        public String encode(String pString)
        {
            return soundex(pString);
        }

        /**
         * Used internally by the SoundEx algorithm.
         * 
         * Consonants from the same code group separated by W or H are treated as one.
         * 
         * @param str
         *                  the cleaned working string to encode (in upper case).
         * @param index
         *                  the character position to encode
         * @return Mapping code for a particular character
         * @throws IllegalArgumentException
         *                  if the character is not mapped
         */
        private char getMappingCode(String str, int index)
        {
            // map() throws IllegalArgumentException
            char mappedChar = this.map(str.charAt(index));
            // HW rule check
            if (index > 1 && mappedChar != '0')
            {
                char hwChar = str.charAt(index - 1);
                if ('H' == hwChar || 'W' == hwChar)
                {
                    char preHWChar = str.charAt(index - 2);
                    char firstCode = this.map(preHWChar);
                    if (firstCode == mappedChar || 'H' == preHWChar || 'W' == preHWChar)
                    {
                        return '0';
                    }
                }
            }
            return mappedChar;
        }

        /**
         * Returns the maxLength. Standard Soundex
         * 
         * @deprecated This feature is not needed since the encoding size must be constant. Will be removed in 2.0.
         * @return int
         */
        public int getMaxLength()
        {
            return this.maxLength;
        }

        /**
         * Returns the soundex mapping.
         * 
         * @return soundexMapping.
         */
        private char[] getSoundexMapping()
        {
            return this.soundexMapping;
        }

        /**
         * Maps the given upper-case character to its Soundex code.
         * 
         * @param ch
         *                  An upper-case character.
         * @return A Soundex code.
         * @throws IllegalArgumentException
         *                  Thrown if <code>ch</code> is not mapped.
         */
        private char map(char ch)
        {
            int index = ch - 'A';
            if (index < 0 || index >= this.getSoundexMapping().Length)
            {
                throw new java.lang.IllegalArgumentException("The character is not mapped: " + ch);
            }
            return this.getSoundexMapping()[index];
        }

        /**
         * Sets the maxLength.
         * 
         * @deprecated This feature is not needed since the encoding size must be constant. Will be removed in 2.0.
         * @param maxLength
         *                  The maxLength to set
         */
        public void setMaxLength(int maxLength)
        {
            this.maxLength = maxLength;
        }

        /**
         * Retrieves the Soundex code for a given String object.
         * 
         * @param str
         *                  String to encode using the Soundex algorithm
         * @return A soundex code for the String supplied
         * @throws IllegalArgumentException
         *                  if a character is not mapped
         */
        public String soundex(String str)
        {
            if (str == null)
            {
                return null;
            }
            str = SoundexUtils.clean(str);
            if (str.length() == 0)
            {
                return str;
            }
            char[] outJ = { '0', '0', '0', '0' };
            char last, mapped;
            int incount = 1, count = 1;
            outJ[0] = str.charAt(0);
            // getMappingCode() throws IllegalArgumentException
            last = getMappingCode(str, 0);
            while ((incount < str.length()) && (count < outJ.Length))
            {
                mapped = getMappingCode(str, incount++);
                if (mapped != 0)
                {
                    if ((mapped != '0') && (mapped != last))
                    {
                        outJ[count++] = mapped;
                    }
                    last = mapped;
                }
            }
            return new String(outJ);
        }

    }
}